Safety control mechanisms



Aug- 28, 1955 F. E. sTRATToN ET/u.

SAFETY CONTROL` MECHANISMS 3 Sheets-Sheet 1 Original Filed March 29. 1949 Aug# 28, 1956 F. E. s'rRATroN ETAL 2,760,616

SAFETY CONTROL MECHANISMS 3 Sheets-Sheet 2 Original Filed March- 29, 1949 ug- 28, 1956 F. E. STRATTON ETAL 2,760,616

SAFETY CONTROL MECHANISMS Original Filed March 29, 1949 3 Sheets-Sheet 5 www United States Patent O 2,760,616 SAFETY CONTROL MECHANISMS Frank E. Stratton and Horatio V. Hall, Beverly, Mass., assgnors to United Shoe Machinery Corporation, Flemington, N. J., a corporation of New Jersey Original application March 29, 1949, Serial No. 84,176, now Patent No. 2,651,365, dated September 8, 1953. Divided and this application December 5, 1952, Serial No. 324,372

2 Claims. (Cl. 192-131) This invention relates to presses and more particularly to safety control mechanisms for safeguarding the operator of the press. The present application is a division of application Serial No. 84,176, iiled March 29, 1949, in the names of Frank E. Stratton and Horatio V. Hall, now United States Letters Patent No. 2,651,365, granted September 8, 1953.

In presses as heretofore constructed various attempts have been made to provide safety mechanism elective to prevent injury to an operator during the operation of the press. In one type of press commonly known as a clicking machine there is a movable beam swung about an axis in one side of the cutting bed and over a cutting block upon which is supported sheet material and a die for cutting a blank from the material. The means for initiating a pressure operation of the beam usually comprises a hand trip by which the beam can be moved over the cutting bed and upon depression of which will initiate a power operation of the beam. In some instances clicking machines have been provided with a second hand trip so arranged that both hands of the operator will be required to initiate operation of the machine thus preventing any likelihood of injurying either hand.

It is an object of the present invention to provide control mechanism for clicking machines in which the use of both hands of the operator is required and one which will be particularly elfective in insuring safety of the operation. To this end and as shown, there is provided manually operable starting means associated with the beam and so constructed and arranged that it is necessary for the operator to use both hands in initiating a power operation of the machine, thus insuring that his hands are in a safe position during operation of the machine. As disclosed herein this mechanism takes the form of two manual controls, operation of both of which is required to close an electric circuit through a solenoid operable to initiate a power operation of the toggles. Repetition of a power operation is prevented by means of electrical devices until both of the manual controls have been released, thus preventing unauthorized jamming of the safety mechanism.

These and other objects and features of the invention are disclosed in the following specification and in the accompanying drawings and are pointed out in the appended claims.

In the drawings,

Fig. 1 is a View in end elevation, partly in section, illustrating one embodiment of the clicking machine constituting our invention;

Fig. 2 is a plan View, partly in section, of the manually operable starting mechanism;

Fig. 3 is a front elevation, partly in section, of the mechanism shown in F ig. 2;

Fig. 4 is a side view, partly in section, of the mechanism shown in Fig. 2;

Fig. 5 is a wiring diagram illustrating the electric circuit employed in the machine. v

As shown in Fig. 1 the machine comprises a platen 10 adapted to support upon its upper face sheet material 12 `and a lcutting die 14 located upon the material with its "ice cutting edge down. Above the platen is located a beam 16 secured to a vertically extending post 18 positioned at one side of the platen and rotatably mounted in the frame 20 of the machine. The beam is movable, by means of a handle 22, about the axis of the post and across the platen 10 into operative position above the die located upon the sheet material. Operatively connected to the platen is mechanism including toggles 24 for moving the platen upwardly toward the beam to present the die into engagement with the beam, for rolling the platen along the beam in eiecting progressive penetration of the cutting edge of the die through the work to produce a blank, and for returning the platen to a rest position.

The toggles 24 are actuated by levers 25 driven by cam mechanism, not shown in detail, from a main shaft 26 through a clutch 27 operable to connect the shaft to a flywheel 28 driven by a motor 29. Movement of the clutch to eifect actuation of the toggles is initiated by means of a solenoid 30 having a plunger 31 for rotating a clutch control lever 32 carrying a link 34 having a latch 33 at its upper end and arranged, when the link is depressed, to release a clutch lever 35 from a pawl 36 thereby permitting a spring 37 to move a bell crank lever 38 in a clockwise direction to eiect engagement of the clutch. At the end of a single revolution of the shaft 26 the pawl 36 reengages the clutch lever 35 to effect release of the clutch whether or not the solenoid 3i) is deenergized. The control lever 32 is ineiective again to operate the clutch lever 35 until the solenoid is deenergized permitting the latch 33 to be reset.

For' a more detailed `description of the mechanism thus far described reference may be had to the aforementioned copending application.

The present invention has to do with the mechanism for controlling the operation of the solenoid in effecting power operation of the machine.

Power operation of the machine is initiated by manually operable mechanism closely associated with the handle 22 and requiring the use of both hands of the operator in actuating separate switches arranged in series in the circuit through the solenoid 30, as shown in Figs. 2, 3 and 4. One of the switches is a push button switch 42 mounted upon a bracket 44 on the beam. The switch is controlled by a member in the form of a lever 46 pivotally mounted on a pin 48 in a recess 50 in the handle and operable by a hand grip 52 secured to the lever. A plunger 54 connected to the lower end of the lever is arranged to actuate the switch 42 when the upper end of the lever is forced toward the axis of the handle by one hand of the operator.

Mounted on a horizontal plunger 56 in a housing 58 on the beam and spaced some distance laterally from the handle are two hand knobs 6i) located upon opposite sides of the beam. Either knob can be pushed inwardly to cause the plunger to trip one of the push button switches 62 or 64 which are arranged in parallel with the switch 42 in the electrical circuit through the solenoid 3). The plunger 56 carries at its central portion a collar 66 pinned to the plunger and arranged for sliding movement in a sleeve 68. On the plunger are loosely mounted two frusto conical members 70 located upon opposite sides of the sleeve and normally forced into engagement with the sleeve by springs 72 on the plunger and bearing on the housing and on the outer ends of the members. The members 70 normally lie adjacent to leaf springs 74 which are secured to the housing and have free end portions of which extend into position adjacent to push buttons 78 of the switches. Outward movement of either of the members 70 results in engagement of the frusto conical surface of the member with its associated spring to depress the switch button. Thus when one of the hand knobs 60 is forced inwardly the collar 66 moves the member 70 on the far side of the sleeve outwardly effecting operation of the adjacent switch. Upon release of the hand knob springs 72 return the collar and the member to neutral positions thus releasing the switch.

The construction and arrangement of the parts just described are such that the beam can be swung over a die located upon the platen by the use of one hand of the operator, the hand gripping the handle 22 in moving the beam into operative position and the fingers being used for operating the hand grip 52 to actuate the switch 42. The other hand is then used to press one of the knobs 60 effecting an operation of one of the switches 62 or 64 to initiate an operation of the machine. Since both hands of the operator are required for operating the switches at points above the contacting faces. of the beam and platen any likelihood of injury to the hands of the operator through operation of the platen is eliminated.

As shown in Fig. 5, the. motor 29 is. supplied from a three-phase power source comprising power lines 80, 82 and 84 which extend through a magnetic motor starter 86. The starter is provided with three contacts 88, 90 and 92 which, when a coil 94 is energized, close the circuits through the power lines 80, 82 and 84 respectively. A conductor 96 connects the power line 80 with one side ot a push button stop switch 98 the other side of the switch being connected by a conductor 100 with one side of a push button start switch 102. The other side of the start switch is connected by a conductor 104 to the coil 94 which is connected to the power line 82. The stop switch is normally closed and the start switch is normally open. When the start switch is depressed current iiows through the coil 94 actuating the motor starter to close the contacts 88, 90 and 92 and starting the motor. The coil 94 is maintained energized by a holding circuit which extends from the power line 82 through the coil 94, the conductor 104, and a conductor 106, through a relay 108, a conductor 110, a contact 112 in the motor starter, and a conductor 114 leading to the conductor 100, and thence through the stop switch 98 to the power line 80. The relay 108 has a contact 116 arranged to be closed upon energization of a coil 118. This coil is in a circuit through the secondary 120 of a transformer 122 the primary 124 of which is supplied current from the power lines 80, 82, thus the motor starting contacts are maintained closed and the motor continues to operate until the stop switch is depressed to break the holding circuit. A conductor 126 connected to one side of the transformer secondary extends to one side of a relay 128. The relay has a coil 130 which when energized closes a contact 132 to conduct current from conductor 126 through the solenoid coil and from thence to a conductor 134 leading to the other side of the transformer secondary. Extending from the conductor 126 is a branch circuit leading through the switches 62 and 64 through a coil 136 of a relay 138 and thence to the conductor 134. Another branch circuit extends from conductor 126 through the switch 42 and a coil 140 of a relay 142 and from thence to conductor 134.

When both relays 138 and 142 are energized through closing the switch 42 and one or another of the switches 62 and 64 current passes from the conductor 126 through contact 144 of relay 138 and through a contact of relay 142 through the coil 130 of relay 128 to conductor 134 thus energizing the relay 128, and closing the contact 132 thus effecting operation of the solenoid 30. This initiates a power operation of the machinev as heretofore described.

As long as the solenoid 30 remains energized the plunger 31 is held inwardly and the link 34 is held down with the result that the latch 33 is held in inoperative position, thus preventing actuation of the link to produce another power operation of the machine.

Solenoid 30 is maintained in energized condition as long as any one of the switches 42, 62 and 64 is held in closed position. This is accomplished by meansof holding circuits to maintain the coil 130 energized with the result that the contact 132 controlling the solenoid circuit is maintained in closed position. If the switch 42 is held closed the coil 140 of the relay 142 is energized as above described and current passes from the conductor 126 through a contact 148 of relay 128 through a conductor 150, through a contact 146 in relay 142, and a conductor 154 to the coil 130 and from thence to conductor 134.

If the switch 42 is open but either of the switches 62 or 64 is closed current passes from conductor 126 through the contact 148 of the relay 128 through the conductor 150, through a contact 152 in the relay 138 which at that time is energized, and through the conductor 154, through the coil and to the conductor 134.

Thus after initial operation of the solenoid 30 in effecting power operation of the machine the solenoid is continued to be energized, through operation of one or another of the holding circuits just described, as long as any of the manually operated switches is held closed. The purpose of this construction and arrangement is to insure the safety of the operator by preventing him from tying back or wedging in closed position one or another of the switches 42, 62, 64, which is sometimes attempted by' an operator in order to speed up his production. By the construction above described after an operator has used both hands to initiate the power operation of the machine he must release the manually operable starting controls in order to permit the resetting of the starting mechanism.

Havingdescribed our invention, what we claim as new and desire to secure by Letters Patent of the United States is;

1. Control mechanism for presses having an electrically operated power means, said control mechanism comprising a solenoid for initiating an operation of the power means, an electric circuit through the solenoid, three normally open relays in the circuit each relay having a coil and a coil operated armature, a manually operable switch for closing the circuit through one of the relays, a second manually operable switch for closing the. circuit through another of the relays, and holding circuits.` through the armature of each of two of the relays when closed and extending through the coil of the third relay when closed for energizing the third relay therebyl to maintain the solenoid circuit closed until both manually operable switches are opened.

2. Control mechanism for presses of the type having an electrically operated power means, said control mechanism comprising a housing, a plunger slidably mounted in the housing and having its ends projecting from opposite sides thereof, knobs on the ends of the plunger, a collar on the plunger and secured to the central portion thereof, a fixed sleeve surrounding the collar, push button switches located adjacent to the sleeve at opposite ends thereof, an electric circuit extending through the switches for controlling the power means, spring contacts for actuating the switches, frusto conical members loosely mounted upon the plunger adjacent to the contacts and positioned with their base portions extending outwardly toward the sleeve and each being movable outwardly by the collar upon the pressing of the knob located upon the opposite side of the sleeve thereby to depress a spring contact to operate one of the switches, and means for normally forcing the frusto conical members into inoperative position in engagement with the sleeve.

References Cited inthe file of this patent UNITED STATES PATENTS 1,556,954 Polk Oct. 13, 1925 1,878,090 Alcoriza Sept. 20, 1932 2,210,886 Dewey Aug. 13, 1940 2,259,257 McBlane Oct. 14, 1941 2,355,119 Stratton Aug. 8, 1944 2,579,595 McLane Dec. 23, 1951 2,639,796 Dean May 26, 1953 

